1. Technical Field
The present invention relates to motorcycles, and more particularly, to motorcycles including an adjustment mechanism for adjusting the position of the shaft.
2. Description of the Background Art
In a motorcycle with a chain for transferring the drive power from the engine, a driving sprocket is provided on the engine and a driven sprocket is provided on the rear wheel. The chain is wound around the driving and driven sprockets. Sometimes, in such a motorcycle, the tension of the chain is adjusted, for example when the chain has increased in length. Typically, a mechanism for adjusting the position of the rear axle is provided at the rear end of a rear arm that supports the rear wheel. The position of the rear axle is adjusted when a rear arm with a different length or a driven sprocket with a different size is used.
For example, JP 2010-167866 A discloses a chain adjust mechanism where an adjuster that supports the rear axle may be moved within a recess formed in the rear end of the rear arm to adjust the position of the rear axle and the tension of the chain. In this chain adjust mechanism, the adjuster is composed of an upper subassembly and a lower subassembly. Thus, as the rear axle is tightened toward the adjuster, the upper subassembly moves upward to be pressed against the upper wall of the recess in the rear arm, while the lower subassembly moves downward to be pressed against the lower wall of the recess in the rear arm. This allows the adjuster, together with the rear axle, to be firmly fastened to the rear arm.
As discussed above, in the motorcycle described in JP 2010-167866 A, the adjuster as well as the rear axle may be firmly fastened to the rear arm. However, some circumstances, such as sport riding or races, may require the rear axle and rear arm to be fastened more firmly to each other to provide better control of the vehicle body.